Heres a set of plugin examples for the manager welcome screen which might be of use.
1. Unzip the attached manager_welcome_screen.zip, upload the manager_welcome_screen folder into your assets/plugins/ folder.
2. Rename your current welcome.html, and drop the modified welcome.html into your assets/templates/manager/ folder.
3. Create a plugin named "manager_welcome_screen" with the code below ( no php tags )
include MODX_BASE_PATH.'assets/plugins/manager_welcome_screen/mws_plugin.php';
check the following events:
OnManagerWelcomePrerender
OnManagerWelcomeHome
OnManagerWelcomeRender
OnDocFormRender